Magnesium-base alloy



...i an");

atenieti May ETEE MAGNESKUM-BASE ALLOY Reginald S. Dean and i'llarence T. Anderson,

Salt e City, Utah, ignore to Chicago Development Company, Chicago, 111., a corporatime or lillinois No Drawing. Application ilctober l, lilill, Serial No. 413,159

3 Claims.

rosion than magnesium-base alloys and that, of

the alloying elements which are conventionally added to magnesium, manganese brings about the least reduction of corrosion resistance. Heretofore, it ha been exceedingly dimcult to add manganese to magnesium in amounts greater than about 1% to 2% manganese without obtaining a non-homogeneous alloy.

In accordance with our invention, manganese may be incorporated into magnesium in substantial amounts, in a relatively simple manner, with- "outihterfering with the desired homogeneity of the resulting alloy. We have found that if lithium is added to magnesium, the amount of manganese which ordinarily can be incorporated with the magnesium without efiecting production of a non-homogeneous alloy may be substantially increased. The amount of manganese which may be incorporated with the magnesium to produce a homogeneous alloy is determined, in part, by the amount of lithium which is present. Thus, for'example, with 5% lithium, .of manganese may be readily incorporated into magnesium with the production of a homogeneous alloy.

In general, ,the alloys of our invention contain from about 1% to about 10% lithium, from about 2% to about 10% manganese, balance substantially all magnesium.

We have also found that the addition of silver to the lithium-manganese-magnesium alloys, described hereinabove, increases their strength in the cold rolled condition and somewhat improves their casting properties. The amount of silver which brings about these properties is of a small order, from about 0.5% to about 2.0% being sufficient in at least most cases.

The following. examples are illustrative of al- I loys made in accordance with our present invention. It will be understood that various changes may be made with respect to proportions of the alloying ingredients, within the ranges set out hereinabove, and that other changes may be made without departing from the pirit of the invention in the light of the guiding principles which are dsclosed herein.

Example 1 &

used for the commercial melting of magnesiumbase alloys may be used to protect the surface of the metal during melting. The alloy, when cast, had a hardness of 27 when measured on the Rockwell F scale. The alloy may be cold rolled by any of the usual processes. When substan-' tially fully cold worked to form a sheet, it has a hardness of measured on the Rockwell 1 scale. The alloy is considerably harder and stronger than at least most other magnesium base alloys which have heretofore been made available. This increased hardness and strength make the alloy particularly valuable for the construction of various parts'oi airplanes.

Example 2 An alloy was made containing 83% magnesium, 10% manganese, 5% lithium, and 2% silver, said alloy being prepared from the same grade of a1- loying elements and in the same manner as described in Example 1. The resulting alloy, when cast, is considerably harder than the alloy of- Example 1. Thus, in the cast condition, it has a hardness of 40 measured on the Rockwell F scale whereas in substantially the fully cold worked condition it has a hardness of measured 0n the Rockwell F scale. The density of the alloy was approximately 2.0. This alloy, like that of the first example, lends itself to all of the usual forms of cold working.

As we have indicated hereinabove, in the practice of our invention weprefer to employ alloying metals of high purity. The magnesium, as we have indicated, is preferably a redistilled product. The manganese, for best results, should be at least 99.0% pure and preferably of even greater purity. The manganese utilized may be produced by a vacuum distillation process but we prefer, particularly, to employ electrolytic manganese having a purity of at least about 99.0% and preferably of 99.9%. The lithium, and silver where used, are also preferably of a high degree of purity.

What we claim as new and desire to protect by Letters Patent of the United States is:

alloys containing from manganese, balance sub- 

